Planoor



W. G. TARRANT.

BUILT UP WOODEN GIRDER.

APPLlcAloN FILED MAR. 21, 1919.

Patented Sept. 30, 1919.

. yf x 'rma COLUMBIA PLANOURAPM co.. WASHINGTON. D. c

WALTER GEORGE TARRANT, or BYELEET, Eiverrinnn.y

BUILT-UP WQODEIN GIRDER.

Specification of Letters Patent.

Patented senese, 1919.

Application ledlvarch 271919. Serial No. 28i5,'26

T0 all LU/tom t may. concern:

Be it known that I, WALTER GEORGE TAR- nAN'r, a subject of the King of Great Eritaiu, residing at Lalreltlouse, Byl'leet,in the county of Surrey, England, have invented a new and useful Il'nproved Built Up lVooden Girder, of which the following is a specification.

rlhis invention relates to the construction of light wooden girders, beams, spars, struts or other parts employed in the framing of aircraft, the main object being to attain maximum strength and rigidity in a necessarily extremely light structure.

My invention is illustrated by the accompanying drawings, in which Figure l is a side elevation showing two girder lengths constructed according to this invention and prepared for joining together in line, Fig. 2 is a side elevation showing the girder lengths joined together in line, Fig. 3 is a cross section on the line 3-3, Fig. 2, Fig. 1l is a cross section on the line fre-t, Fig. 2, Figs. 5 and 6 are detail views of a joining web of three ply veneer and Figs. 7 and S show details.

Figs. 1 and 2 show two lengths of girder each of which comprises four longitudinal members each comprising two wooden beams as, a, of tapered form as seen in cross section and having on their inner surfaces longitudinal grooves Z). c, c, are inclined braces also formed of wood and having beads CZ formed on each side of each end: these beads lie in the grooves b as is clearly to be seen in Fig. 3, the braces being glued to the beads. The braces connecting two of the members are at right angles to the braces connecting the other members so thatV the whole structure is cruciform in cross section as seen in Fig. 4.

Reinforcing ribs e are applied at an angle to the grain and so shaped as to give great vstrength and resistance to deformation under the stresses imposed particularly at or near the middle of the length of the brace are glued to the braces. Beaded filling pieces are inserted between the beams a of each member and are glued in position extending from one brace to the next.

The two girder lengths are connected together by a web g of ply wood of the same thickness as the braces c; this web has beads Z1 which lie in the grooves Z9 and is glued to the abutting ends of the members of the two lengths, the joints between the various members being staggered so that they may not.

rl`on opposite faces oi otherwise smooth p ly wood is illustrated in Fig. G and consists 1n boring through the wood a iow of equally spaced holes and lacing through the holes from side to side in succession a string of wood fiber all. `When in position the string forms an interrupted bead on each side of the web and is hardened and fixed by the application of glue.

i, z', are slots in the web for allowing the braces c to pass through it.

The two webs g connecting opposite members of the girder lengths are slotted as shown in Fig. 7 to enable them to be arranged at right angles to one another as shown in Fig. 8.

Vhat l claim is l. The combination of two parallel members each comprising a pair of wooden beams each of which has on its inner face a longi tudinal groove, and a plurality of inclined braces connecting the two members and having at their ends beads lying in the grooves.

2. The combination of four members each comprising two wooden beams having longitudinal grooves on their inner aces and two series of inclined braces connecting opposite members and having at their ends beads lying in the grooves, the two series of braces being arranged in two planes which are at right angles to one another.

3. The combination of two pairs of par.- allel members each comprising a pair of wooden beams each of which has on its inner face a longitudinal groove, one end of each member of one pair butting against the end of a member of the other' pair, a plurality of inclined braces connecting the two members of each pair and having at their ends beads lying in the grooves and the braces connecting the two members of one pair lying in a plane at right angles to that in which lie the braces connecting the members of the other pair, and a beaded web connecting the pairs of members and having its beads lying in the grooves.

4L. The combination of two sets of four members each member comprising two wooden beams having longitudinal grooves on their inner faces, two series of inclined braces connecting the opposite members of each set and having at their ends beads lybers each comprising a pair of wooden ing in the grooves, the two series of braces of each set being arranged at right angles to one another and one end of each member of one set butting against an end of a member of the other set, and two webs each of which is connected along each of two opposite edges to one member of each set, the two webs being arranged at right angles to one another.

5. The combination of two parallel mem- Goplel of this patent may be obtained for beams each of which has on'vits inner face a longitudinal groovea plurality of 1nolined beaded braces connecting the twoV members and a plurality of beaded lllng as my invention I have signed my name this 20 21st day of February,` 1919. f

WALTER GEORGE TARRANT.

tive cents each, by addressing the Commissioner o! Patents. Washington, D. G. 

